1. Field of the Invention
This invention relates to an internal combustion engine with a water-cooling intercooler.
2. Description of the Prior Art
A representative example of a water-cooling intercooler of a cooling system which has been proposed so far is shown in FIGS. 13 and 14. FIG. 13 shows a system diagram of the flow of cooling water for cooling an intercooler 50. The cooling water for cooling the intercooler 50 flows in a cooling system disposed independently of an engine cooling system (not shown), and is circulated between the intercooler 50 and a sub-radiator 53 by an electric water pump 52 provided exclusively for the intercooler 50. The cooling water got through the heat-exchange in the intercooler 50 is delivered to the sub-radiator 53 disposed at the front of a vehicle, and is cooled by an engine cooling fan (not shown) and by the wind resulting from the travelling vehicle. The cooling water thus cooled is again introduced into the intercooler 50. In FIG. 13, an air cleaner is designated at 54, a turbocharger is designated at 55, and a surge tank is designated at 56.
Turning now to FIG. 14, the figure shows a tandem type centrifugal water pump 57 proposed in Japanese Unexamined Patent Publication No. 27810/1983. The water pump 57 has a housing 59 rotatably holding a rotary impeller 58. The rotary impeller 58 is fixed on a drive shaft 61 with a pulley 60 installed at one end thereof. The rotary impeller 58 forms a first fluid chamber 63 and a second fluid chamber 64 together with an inner partition member 62 formed integrally in the housing 59, and has first vanes 67 formed integrally thereon for the first fluid chamber 63 and second vanes 68 formed integrally thereon for the second fluid chamber 64. The first fluid chamber 63 is connected to a water jacket of an engine, an inlet port (not shown) and an outlet port (not shown). The second fluid chamber 64 is communicated with an air-fluid heat exchanger, and is connected to the other inlet port (not shown) and an outlet port 65. A sealing member 66 is placed between the inner partition member 62 and the rotary impeller 58 which separates the first fluid chamber 63 and the second fluid chamber 64 independently of each other.
The two cooling water circuits for the engine and the water-cooling intercooler 50 shown in FIG. 13 do not communicate with each other, and the cooling water temperatures thereof are controlled independently. Consequently, when cold-starting the engine, the intake air should be heated by a certain method, i.e., employing an electric heater or utilizing the heat of the exhaust gas, in order to avoid icing at the throttle of the throttle valve and facilitate the vaporization of the gasoline.
Further, the centrifugal water pump 57 shown in FIG. 14 delivers the cooling water for the intercooler and the engine with the first vanes 67 and the second vanes 68 of the rotary impeller 58 provided on the single drive shaft 61. According to the description of Japanese Unexamined Patent Publication No. 27810/1983, a separator wall 69 of the rotary impeller 58 for holding the sealing member 66 is adjusted with the partition member 62 so as to substantially shut off the cooling water flow between the first fluid chamber 63 and the second fluid chamber 64. Therefore, the two cooling water circuits are also disposed independently of each other in the centrifugal water pump 57 shown in FIG. 14 as described in the cooling system shown in FIG. 13, and the intake air should also be heated by a certain method when cold-starting the engine.